This application relates to a sealed compressor wherein hot oil is moved into contact with a protector switch to shut down the compressor motor in the event that adverse conditions are occurring in the compressor.
Sealed compressors are utilized in most refrigerant compression applications. In a typical sealed compressor, an electric motor drives a compressor pump unit to compress a refrigerant. The refrigerant passes from the compressor pump unit to downstream locations in a refrigeration cycle. There are challenges with operation of sealed compressors. In some cases, there may be a loss of refrigerant within the system. This so-called loss of charge operation can have detrimental effects on the compressor pump unit. When there is an unusually low amount of refrigerant being compressed, the compressor pump components may become hot. This is undesirable.
One popular type of modern compressor pump unit is a scroll compressor pump unit. In a scroll compressor pump unit, a first scroll member has a base and a generally spiral wrap extending from the base. A second scroll member has a base and a generally spiral wrap extending from its base. The wraps of the two scroll members interfit to define compression chambers. The second scroll member is caused to orbit relative to the first, and as the two orbit, compression chambers between the two wraps decrease in volume to compress an entrapped refrigerant.
Scroll compressors are often powered by a three phase electric motor. Three phase electric motors receive three power connections to drive the motor. Occasionally, when the motor is being connected to its power supply, the phase of the three connections are improperly aligned. When this occurs, the motor may be driven in a reverse direction than that which is expected. When a scroll compressor is driven to rotate in the reverse direction, then the refrigerant which Has typically been moved from a radially outer area towards a central area moves in the opposed direction. This is undesirable, and causes the generation of a good deal of heat within the compressor pump unit.
Various methods for identifying reverse rotation and loss of charge situations in sealed compressors have been proposed. However, it would be desirable to provide a simple and yet sure method for identifying such adverse conditions, and stopping operation of a motor when such adverse conditions are identified.